1. Field of the Invention
The present invention relates to anti-armor projectiles and, more particularly, is directed towards anti-armor projectiles comprising a main projectile and an additional autonomous precursor warhead which can be stowed with and attached to the main projectile just prior to firing, thereby providing a tandem warhead capability and improved lethality for the main projectile. More particularly, this invention provides an attachable warhead which is packaged with a main projectile so that the length of the main projectile remains unchanged while it is stored and until the autonomous warhead is attached just prior to firing. The autonomous warhead may be a chemical energy (CE) warhead or a kinetic energy (KE) warhead so that when attached to main projectiles having CE warheads or KE warheads, tandem CE-CE, tandem CE-KE, tandem KE-KE, or tandem KE-CE warhead projectiles are created. As used herein, tandem X-Y indicates that X is the additional precursor, or first warhead to impact the target, and Y is the main or second warhead to impact the target.
2. Description of the Related Art
Chemical energy warheads, also known as shaped-charge warheads, are formed by a metallic liner and an explosive shaped charge, both of which are contained within and carried on board the projectile. The shaped charge is positioned behind the liner, with respect to the direction of flight, so that when the charge is detonated the liner forms a metallic jet directed at the target. The chemical energy warhead must be activated only very near the target at what is known as the "standoff" distance (usually less than 1-2 meters). The standoff is the distance between a chemical energy warhead and the target at the moment of detonation of the shaped or hollow charge. The effect of the warhead depends on the standoff, which is usually optimal at a distance of about 4 times the diameter of the charge. Detonation of the charge at a distance too great from the target results in break-up of the metallic jet and decreased lethality against heavily armored targets.
Standard chemical energy warhead projectiles typically include a spacer or spike located at the front end of the projectile to provide the aforementioned standoff distance. When an impact fuse is mounted on the tip of the spacer, it detonates the shaped charge at the moment of impact so that the jet is formed within the standoff distance from the target. Alternatively, a proximity fuse may be used in lieu of the impact fuse to ensure detonation at a proper standoff distance.
Anti-armor kinetic energy projectiles carry long rods or penetrators which are launched from large caliber gun tubes at very high velocities. For effective lethality, these velocities are usually several times the speed of sound. The mass of these projectiles, along with the speed, determines the kinetic energy that will be transferred to the target on impact. This kinetic energy, E, is represented by 1/2(mass).times.(velocity).sup.2. The objective of these projectiles is to penetrate heavy armor and other targets with the most energy and lethality, therefore, the penetrators are usually made of high-density materials such as depleted uranium or tungsten.
Tandem warheads are well known in the art, having been designed for missile systems over the past two decades. "Tandem" refers to two or more warheads (usually CE-CE in missiles) of similar or different diameters being carried on board the same missile. These tandem (CE-CE) warheads are known to be effective against reactive armor, where the first (usually called precursor) warhead activates the armor while the second main warhead follows to defeat the target. See, for example, U.S. Pat. Nos. 4,848,238 and 5,744,746 for tandem CE-CE warheads of the prior art. Tandem chemical energy warheads are used worldwide in missile systems, for example, in the modified TOW missile family series. "Dual" warheads are sometimes used in missiles, for example, to produce top-attack explosively formed projectiles (EFPs), but dual warheads differ from tandem warheads in that dual warheads are not designed to hit the same point on the target.
For projectile applications, tandem kinetic energy warheads (KE-KE) are also known in the art. For example, see U.S. Pat. No. 4,878,432 for a multistage kinetic energy penetrator. In addition, hybrid chemical energy-kinetic energy (CE-KE) tandem warhead projectiles are also known in the art. The French are known to have designed a CE-KE tandem projectile with an impact fuse for the front CE warhead. Furthermore, see U.S. Pat. No. 4,497,253 for a CE-KE tandem warhead having a proximity fuse for the front CE warhead. In addition, U.S. Pat. No. 4,102,271 discloses a projectile having a main CE warhead and a forward armor-penetrating device with an axial conduit in communication with the main explosive charge warhead.
In all of this tandem warhead prior art, the two warheads are fixed together as one piece within the projectile body. This arrangement does not pose a problem for missile applications, which are usually not strictly limited or restricted to a particular length or diameter, i.e., the total length or diameter of the missile is not critical. However, for projectile applications the total length of the projectile is limited by the corresponding length available in the munition storage space, for example, in the bustle of a combat tank. The bustle is the munitions storage rack inside the tank. A spacer or spike of about 6-8 inches is usually required at the front of a projectile as the standoff distance ahead of each CE warhead. This will cause a tandem CE-CE projectile to be too long to be practical for handling by soldiers and, more importantly, for storage in current combat tank bustles. Moreover, for current kinetic energy single-warhead long penetrators, the total length of current rod designs is approaching the maximum allowed length in U.S. and NATO tank bustles, with only a few centimeters (or millimeters for some projectiles) to spare. Thus, adding a second chemical energy warhead to current kinetic energy long penetrator warheads is not possible without modification or redesign of the current tank turret, which is a costly and undesirable alternative.
The present invention provides an autonomous precursor warhead that can be attached to main projectiles thereby creating tandem CE-CE, CE-KE, KE-KE, or KE-CE warheads without the need for more storage space in tank turret bustles because the projectile's overall length remains within allowable limits until just prior to firing. The autonomous, attachable precursor warhead is self-contained, packaged with the main projectile, and is attached to the main projectile only just before ramming the projectile inside the gun tube for firing. Thus, it does not require added storage length or space for the munition cartridge. By "autonomous", it is meant here that the attachable precursor warhead is self-contained and requires no external elements for preparation or functioning. In other words, after mounting the attachable warhead to the main projectile, through threads and a screwing motion or by other attachment means, the now tandem warhead projectile would be ready for use and firing.